1. Field of the Invention.
The present invention relates generally to gear drives and in particular to a combination gear drive with a clutch assembly including drive and non-reverse clutch mechanisms.
2. Description of the Prior Art.
Gear drives are well known in the art and a variety of designs have heretofore been proposed for various applications. For example, right angle gear drives are often employed with above-ground engines for driving vertical shafts connected to below-ground pumps. Such arrangements are commonly found in irrigation, petroleum production and various civil and sanitary pumping installations. An exemplary right angle gear drive interconnecting an engine and a deep well pump is shown in U.S. Pat. No. 3,417,636 to T. D. Randolph for HEAT TRANSFER APPARATUS.
In certain applications, continuous operation is required and a backup or auxiliary engine or motor may be coupled to the gear drive. A common arrangement includes an electric motor for normal operation with a gasoline or diesel engine as a backup. Automatic control systems may be provided which start the backup engine in response to a loss of power to the primary motor.
Such gear drives with multiple inputs are referred to as combination drives. Typical applications include storm drainage pumps for tunnels and underpasses, sewage lift stations, municipal water supply systems and pumps for fire fighting equipment.
Combination gear drives are generally provided with clutch mechanisms for disengaging the backup engine during normal operation. For example, manual clutches are provided in many combination drives. However, they require the presence of an operator to make the conversion from normal to backup operation, which may require the partial disassembly and modification of the combination drive unit to engage the clutch.
Most combination gear drives also require non-reverse mechanisms to prevent backwards rotation of the pumps driven thereby. Otherwise liquid upstream of the pump would tend to rotate it backwards when the motor or engine is stopped. Such backwards rotation can damage the impeller and other parts of the pump, and if sufficiently forceful can lift the pump and gear drive off of their mountings. This problem is most severe in deep hole applications where a substantial head of liquid accumulates over the pump.
Transmission-type clutches with sprag non-reverse mechanisms have heretofore been employed in gear drives. Such clutches allow slippage in one direction, for example, when the gear drive is operating, but prevent movement in the opposite direction. However, the sprags are subjected to considerable sliding friction and thus have relatively short operating lives, even when lubricated with transmission fluid or the like. Furthermore, lubrication systems for the sprags tend to add complexity and expense to the gear drives, and if the clutch lubrication system malfunctions, damage can result in a relatively short time.
Heretofore, there has not been available a combination gear drive with drive and non-reverse clutches having the advantages and features of the present invention.